Method of manufacturing a printed circuit board

ABSTRACT

A method of manufacturing a printed circuit board, according to one embodiment, includes forming a circuit pattern and a via pad, which is disposed by being spaced apart from the circuit pattern and has concavo-convex patterns, on a first insulating layer; forming a second insulating layer on the circuit pattern and the via pad having the concavo-convex patterns formed thereon; forming a via hole by etching a portion of the second insulating layer on the via pad; and forming a copper foil layer on the second insulating layer having the via hole formed therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. divisional application filed under 37 CFR1.53(b) claiming priority benefit of U.S. Ser. No. 12/656,643 filed inthe United States on Feb. 5, 2010, now allowed, which claims earlierforeign priority benefit of Korean Patent Application No.10-2009-0104212 filed with the Korean Intellectual Property Office onOct. 30, 2009, the disclosure of all of which are incorporated herein byreference.

BACKGROUND

1. Field

The present invention relates to a printed circuit board including a viapad with concavo-convex patterns of various shapes and a method ofmanufacturing the same.

2. Description of the Related Art

A printed circuit board (PCB) is a circuit board which plays a role ofelectrically connecting or mechanically fixing predetermined electroniccomponents and consists of an insulating layer made of a phenol resin oran epoxy resin and a copper foil layer attached to the insulating layerand having a predetermined wiring pattern formed thereon.

At this time, the PCBs are classified into a single-sided PCB in whichwiring is formed on one surface of an insulating layer, a double-sidedPCB in which wirings are formed on both surfaces of an insulating layer,and a multilayer PCB in which wirings are formed in a plurality oflayers, according to the number of stacked layers.

Recently, high density of a build-up substrate is required due tominiaturization, thickness reduction, and high density of electronicproducts, and a high reliability substrate is required at the same time.

Like this, in order to secure high reliability of the substrate, aninsulating material having a low coefficient of thermal expansion (CTE)and a high glass transition temperature has been developed, and in orderto improve via connection reliability, a laser via, a desmear solution,and a process have been actively developed.

In general, a via hole is formed on the PCB by laser drilling.

The via hole is formed on a circular or square via pad, which is formedon an insulator, by laser drilling. An upper portion and a lower portionof the via hole are plated by electroless plating or electroplating tobe electrically connected to each other.

The shape of the general via pad is larger than a diameter of a bottomof the via hole, and the via pad is formed by copper plating. However,there is a problem of a plating thickness difference due to an areadifference between a region where the circuit pattern is formed and aregion where the via pad is formed.

SUMMARY

The present invention has been proposed in order to solve theabove-described problems, and it is, therefore, an object of the presentinvention to provide a printed circuit board including a via pad withconcavo-convex patterns capable of securing reliability of viaconnection and improving uniformity of via pad thickness, and a methodof manufacturing the same.

In accordance with an aspect of the present invention to achieve theobject, there is provided a printed circuit board including: a circuitpattern formed on a first insulating layer; a via pad disposed on thefirst insulating layer by being spaced apart from the circuit pattern,formed on a lower surface, where a via hole is formed, to have a crosssection larger than that of the via hole, and having concavo-convexpatterns; a second insulating layer formed on the via pad where the viahole is not formed and on the circuit pattern; and a copper foil layerformed on the second insulating layer and the via hole.

In accordance with another aspect of the present invention to achievethe object, there is provided a printed circuit board including: acircuit pattern formed by etching a portion of a first insulating layer;a via pad formed by etching a portion of the first insulating layer,disposed by being spaced apart from the circuit pattern, formed on alower surface, where a via hole is formed, to have a cross sectionlarger than that of the via hole, and having concavo-convex patterns; asecond insulating layer formed on the via pad where the via hole is notformed and on the circuit pattern; and a copper foil layer formed on thesecond insulating layer and the via hole.

Further, the concavo-convex patterns of the printed circuit board inaccordance with the present invention may be formed in at least one of acircular shape, a hexagonal shape, a square shape, a spiral shape, and ashape formed by crossing a plurality of diagonal lines.

Further, the first insulating layer of the printed circuit board inaccordance with the present invention may be made of polyimide.

Further, the circuit pattern or the via pad of the printed circuit boardin accordance with the present invention may be formed of a copper foillayer.

Further, the concavo-convex patterns of the printed circuit board inaccordance with the present invention may be formed by laserirradiation.

Further, the concavo-convex patterns of the printed circuit board inaccordance with the present invention may be formed by etching some orall of the thickness of the via pad.

Further, the concavo-convex patterns of the printed circuit board inaccordance with the present invention may be formed by etching the viapad and portions of the first insulating layer on a lower surface of thevia pad.

In accordance with still another aspect of the present invention toachieve the object, there is provided a method of manufacturing aprinted circuit board including the steps of: forming a circuit patternand a via pad, which is disposed by being spaced apart from the circuitpattern and has concavo-convex patterns, on a first insulating layer;forming a second insulating layer on the circuit pattern and the via padhaving the concavo-convex patterns formed thereon; forming a via hole byetching a portion of the second insulating layer on the via pad; andforming a copper foil layer on the second insulating layer having thevia hole formed therein.

In accordance with still another aspect of the present invention toachieve the object, there is provided a method of manufacturing aprinted circuit board including the steps of: forming a circuit patternby etching a portion of a first insulating layer and forming a via padwith concavo-convex patterns by etching a portion of the firstinsulating layer spaced apart from the circuit pattern; forming a secondinsulating layer on the circuit pattern and the via pad having theconcavo-convex patterns formed thereon; forming a via hole by etching aportion of the second insulating layer on the via pad; and forming acopper foil layer on the second insulating layer having the via holeformed therein.

Further, in the step of forming the via pad with the concavo-convexpatterns of the method of manufacturing the printed circuit board inaccordance with the present invention, the concavo-convex patterns maybe formed by etching portions of the via pad through laser irradiation.

Further, in the step of forming the via pad with the concavo-convexpatterns of the method of manufacturing the printed circuit board inaccordance with the present invention, the concavo-convex patterns maybe formed in at least one of a circular shape, a hexagonal shape, asquare shape, a spiral shape, and a shape formed by crossing a pluralityof diagonal lines.

Further, in the step of forming the via pad with the concavo-convexpatterns of the method of manufacturing the printed circuit board inaccordance with the present invention, the concavo-convex patterns maybe formed by etching some or all of the thickness of the via pad.

Further, in the step of forming the via pad with the concavo-convexpatterns of the method of manufacturing the printed circuit board inaccordance with the present invention, the concavo-convex patterns maybe formed by etching the via pad and portions of the first insulatinglayer formed on a lower surface of the via pad.

Further, in the step of forming the via pad with the concavo-convexpatterns of the method of manufacturing the printed circuit board inaccordance with the present invention, the concavo-convex patterns maybe regularly formed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present generalinventive concept will become apparent and more readily appreciated fromthe following description of the embodiments, taken in conjunction withthe accompanying drawings of which:

FIG. 1 is a view showing a cross section of a printed circuit board inaccordance with a first embodiment of the present invention;

FIG. 2 is a view showing a cross section of a printed circuit board inaccordance with a second embodiment of the present invention;

FIGS. 3A and 3B are views showing the shape of concavo-convex patternsin accordance with a first embodiment of the present invention;

FIGS. 4A and 4B are views showing the shape of concavo-convex patternsin accordance with a second embodiment of the present invention;

FIGS. 5A and 5B are views showing the shape of concavo-convex patternsformed on a via pad in accordance with a third embodiment of the presentinvention;

FIGS. 6A to 6F are views showing the shape of concavo-convex patternsformed on a via pad in accordance with an embodiment of the presentinvention;

FIGS. 7B to 7E are views showing a method of manufacturing a printedcircuit board in accordance with a first embodiment of the presentinvention; and

FIGS. 8A to 8E are views showing a method of manufacturing a printedcircuit board in accordance with a second embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

As the invention allows for various changes and numerous embodiments,particular embodiments will be illustrated in the drawings and describedin detail in the written description. However, this is not intended tolimit the present invention to particular modes of practice, and it isto be appreciated that all changes, equivalents, and substitutes that donot depart from the spirit and technical scope of the present inventionare encompassed in the present invention.

A printed circuit board including a via pad with concavo-convex patternsand a method of manufacturing the same in accordance with certainembodiments of the present invention will be described below in detailwith reference to the accompanying drawings. Those components that arethe same or are in correspondence are rendered the same referencenumeral regardless of the figure number, and redundant explanations areomitted.

<Printed Circuit Board including Via Pad with Concavo-Convex Patterns>

First Embodiment

FIG. 1 is a view showing a cross section of a printed circuit board inaccordance with a first embodiment of the present invention.

As shown in FIG. 1, a printed circuit board including a via pad withconcavo-convex patterns in accordance with a first embodiment of thepresent invention includes a first insulating layer 11, a circuitpattern 12, a via pad 13 having concavo-convex patterns 13A and 13Bformed thereon, a second insulating layer 14, and a copper foil layer15.

The first insulating layer 11 is made of polyimide, and the circuitpattern 12 is formed on one or both surfaces of the first insulatinglayer 11.

The via pad 13 is disposed on the first insulating layer 11 by beingspaced apart from the circuit pattern 12 and formed on a lower surfacewhere a via hole A is formed. A cross section of the via pad 13 islarger than a lower cross section of the via hole A formed on an uppersurface thereof, and the concavo-convex patterns 13A and 13B are formedon the via pad 13.

FIGS. 6A to 6F are views showing the shape of concavo-convex patternsformed on a via pad in accordance with an embodiment of the presentinvention.

As shown in FIGS. 6A to 6F, the concave-convex patterns 13A and 13Bformed on the via pad 13 are formed in at least one of a circular shape,a hexagonal shape, a square shape, a spiral shape, and a shape formed bycrossing a plurality of diagonal lines.

The concavo-convex patterns 13A and 13B are formed on the via pad 13 byforming a circular or square copper plating layer (FIG. 6A) andirradiating laser after forming windows in portions of the copperplating layer or performing plating on portions where a mask is notformed after forming the mask.

The above method of forming the concavo-convex patterns 13A and 13B isjust one embodiment, and the concavo-convex patterns 13A and 13B may beformed by various methods.

Further, the concavo-convex patterns 13A and 13B may be formed byetching some or all of the thickness of the via pad 13 or by etching thevia pad 13 and portions of the first insulating layer formed on a lowersurface of the via pad 13.

FIGS. 3A, 3B, 4A, 4B, 5A, and 5B are views showing the shape ofconcavo-convex patterns in accordance with embodiments of the presentinvention.

FIGS. 3A and 3B show the shape of concavo-convex patterns 13A and 13Bformed by etching all of the thickness of the via pad 13, and a secondinsulating layer 14 stacked between the concavo-convex patterns 13A and13B is all etched.

FIGS. 4A and 4B show the shape of concavo-convex patterns 13A and 13Bformed by etching some of the thickness of the via pad 13, and a secondinsulating layer 14 stacked between the concavo-convex patterns 13A and13B partially remains.

FIGS. 5A and 5B show the shape of concavo-convex patterns 13A and 13Bformed by etching all of the via pad 13 and portions of a firstinsulating layer 11 formed on a lower surface of the via pad 13.

The concavo-convex patterns 13A and 13B shown in the above FIGS. 3A to5B may be differently formed by adjusting the amount of laserirradiation or formed in different shapes by other methods.

The second insulating layer 14 is formed on the via pad 13 where the viahole A is not formed and on the circuit pattern 12, and the copper foillayer 15 is formed on the second insulating layer 14 and the via hole Ato be electrically connected to an upper circuit pattern.

Second Embodiment

FIG. 2 is a view showing a cross section of a printed circuit board inaccordance with a second embodiment of the present invention.

As shown in FIG. 2, a printed circuit board including a via pad withconcavo-convex patterns in accordance with a second embodiment of thepresent invention includes a first insulating layer 11, a circuitpattern 12, a via pad 13 having concavo-convex patterns 13A and 13Bformed thereon, a second insulating layer 14, and a copper foil layer15.

When compared with a printed circuit board in accordance with a firstembodiment, the printed circuit board in accordance with a secondembodiment has differences in a region where the circuit pattern 12 isformed and a region where the via pad 13 having the concavo-convexpatterns 13A and 13B formed thereon is formed.

The first insulating layer 11 is made of polyimide, and portions of oneor both surfaces thereof are etched, and the circuit pattern 12 and thevia pad 13 are formed in the etched portions of the first insulatinglayer 11.

The via pad 13 is disposed by being spaced apart from the circuitpattern 12 and formed on a lower surface where a via hole A is formed. Across section of the via pad 13 is larger than a lower cross section ofthe via hole A formed on an upper surface thereof, and theconcavo-convex patterns 13A and 13B are formed on the via pad 13.

That is, while a circuit pattern 12 and a via pad 13 of the printedcircuit board in accordance with a first embodiment are formed on thefirst insulating layer 11, the circuit pattern 12 and the via pad 13 ofthe printed circuit board in accordance with a second embodiment areformed in the etched portions of the first insulating layer 11.

Therefore, the circuit pattern 12 and the via pad 13 of the printedcircuit board in accordance with a second embodiment are formed byforming the first insulating layer 11, forming trenches in portions ofthe first insulating layer 11, and plating inside the trenches.

Since a cross section of a via pad of a conventional printed circuitboard is different from a cross section of a circuit pattern, it causesa deposition rate difference in a plating process, and due to this,there is a problem that the via pad is non-uniformly plated.

However, since the via pad 13 of the printed circuit board of thepresent invention includes the concavo-convex patterns 13A and 13B tominimize a cross section difference with the circuit pattern 12, it ispossible to uniformly form a plating layer.

Further, since the plating layer is formed between the concavo-convexpatterns 13A and 13B, it is possible to improve via connection strength.

<Method of Manufacturing Printed Circuit Board including Via Pad withConcavo-Convex Patterns>

First Embodiment

FIGS. 7B to 7E are views showing a method of manufacturing a printedcircuit board in accordance with a first embodiment of the presentinvention.

As shown in FIGS. 7B to 7E, a method of manufacturing a printed circuitboard including a via pad with concavo-convex patterns in accordancewith a first embodiment of the present invention forms a circuit pattern12 and a via pad 13 with concavo-convex patterns 13A and 13B on a firstinsulating layer 11 (referring to FIG. 7B).

Here, the concavo-convex patterns 13A and 13B are formed by etchingportions of the via pad 13 through laser irradiation or performingselective plating after forming a mask.

The concavo-convex patterns 13A and 13B are formed in one of a circularshape, a hexagonal shape, a square shape, a spiral shape, and a shapeformed by crossing a plurality of diagonal lines and formed regularly.

Further, the concavo-convex patterns 13A and 13B are formed by etchingsome or all of the thickness of the via pad 13 or by etching the via pad13 and portions of the first insulating layer 11 (referring to FIGS. 3Ato 5B).

Next, a second insulating layer 14 is formed on the circuit pattern 12and the via pad 13 having the concavo-convex patterns 13A and 13B formedthereon (referring to FIG. 7B), and a via hole A is formed by etching aportion of the second insulating layer 14 (referring to FIG. 7C).

After a copper foil layer 15 is formed on the insulating layer 14 havingthe via hole A formed therein (referring to FIG. 7D), copper plating 16is performed on the copper foil layer 15 (referring to FIG. 7E).

Second Embodiment

FIGS. 8A to 8E are views showing a method of manufacturing a printedcircuit board in accordance with a second embodiment of the presentinvention.

As shown in FIGS. 8A to 8E, a method of manufacturing a printed circuitboard including a via pad with concavo-convex patterns in accordancewith a second embodiment of the present invention forms a circuitpattern 12 by etching a portion of a first insulating layer 11 and formsa via pad 13 with concavo-convex patterns 13A and 13B in the etchedportion of the first insulating layer 11, which is spaced apart from thecircuit pattern 12 (referring to FIG. 8A).

Here, the concavo-convex patterns 13 and 13B are formed by etchingportions of the via pad 13 through laser irradiation or performingselective plating after forming a mask.

The description of the shape and features of the concavo-convex patterns13A and 13B is the same as that of a method of manufacturing a printedcircuit board in accordance with a first embodiment.

Next, a second insulating layer 14 is formed on the circuit pattern 12and the via pad 13 having the concavo-convex patterns 13A and 13B formedthereon (referring to FIG. 8B), and a via hole A is formed by etching aportion of the second insulating layer 14 (referring to FIG. 8C).

After a copper foil layer 15 is formed on the second insulating layer 14having the via hole A formed therein (referring to FIG. 8D), copperplating 16 is performed on the copper foil layer 15 (referring to FIG.8E).

When compared to the method of manufacturing the printed circuit boardin accordance with a first embodiment, the method of manufacturing theprinted circuit board in accordance with a second embodiment has adifference in that the circuit pattern 12 and the via pad 13 aredisposed in the etched portions of the first insulating layer 11.

In embodiments of the present invention, since the total plating area isincreased as much as the concavo-convex patterns formed on the via padand it is possible to form a three-dimensional connection surface, thereis an effect of improving via connection reliability and strength.

Further, by forming the concavo-convex patterns on the via pad, it ispossible to maintain a similar deposition rate in a plating process byminimizing an area difference between the via pad and the peripheralcircuit pattern and to uniformly form the plating thickness of the viapad and the circuit pattern.

Although a few embodiments of the present general inventive concept havebeen shown and described, it will be appreciated by those skilled in theart that changes may be made in these embodiments without departing fromthe principles and spirit of the general inventive concept, the scope ofwhich is defined in the appended claims and their equivalents.

What is claimed is:
 1. A method of manufacturing a printed circuit boardcomprising: forming a circuit pattern and a via pad, which is disposedby being spaced apart from the circuit pattern and has concavo-convexpatterns, on a first insulating layer; forming a second insulating layeron the circuit pattern and the via pad having the concavo-convexpatterns formed thereon; forming a via hole by etching a portion of thesecond insulating layer on the via pad; and forming a copper foil layeron the second insulating layer having the via hole formed therein.
 2. Amethod of manufacturing a printed circuit board comprising: forming acircuit pattern by etching a portion of a first insulating layer andforming a via pad with concavo-convex patterns by etching a portion ofthe first insulating layer spaced apart from the circuit pattern;forming a second insulating layer on the circuit pattern and the via padhaving the concavo-convex patterns formed thereon; forming a via hole byetching a portion of the second insulating layer on the via pad; andforming a copper foil layer on the second insulating layer having thevia hole formed therein.
 3. The method according to claim 1, wherein informing the via pad with the concavo-convex patterns, the concavo-convexpatterns are formed by etching portions of the via pad through laserirradiation.
 4. The method according to claim 1, wherein in forming thevia pad with the concavo-convex patterns, the concavo-convex patternsare formed in at least one of a circular shape, a hexagonal shape, asquare shape, a spiral shape, and a shape formed by crossing a pluralityof diagonal lines.
 5. The method according to claim 1, wherein informing the via pad with the concavo-convex patterns, the concavo-convexpatterns are formed by etching some or all of the thickness of the viapad.
 6. The method according to claim 1, wherein in forming the via padwith the concavo-convex patterns, the concavo-convex patterns are formedby etching the via pad and portions of the first insulating layer formedon a lower surface of the via pad.
 7. The method according to claim 1,wherein in forming the via pad with the concavo-convex patterns, theconcavo-convex patterns are regularly formed.
 8. The method according toclaim 2, wherein in forming the via pad with the concavo-convexpatterns, the concavo-convex patterns are formed by etching portions ofthe via pad through laser irradiation.
 9. The method according to claim2, wherein in forming the via pad with the concavo-convex patterns, theconcavo-convex patterns are formed in at least one of a circular shape,a hexagonal shape, a square shape, a spiral shape, and a shape formed bycrossing a plurality of diagonal lines.
 10. The method according toclaim 2, wherein in forming the via pad with the concavo-convexpatterns, the concavo-convex patterns are formed by etching some or allof the thickness of the via pad.
 11. The method according to claim 2,wherein in forming the via pad with the concavo-convex patterns, theconcavo-convex patterns are formed by etching the via pad and portionsof the first insulating layer formed on a lower surface of the via pad.12. The method according to claim 2, wherein in forming the via pad withthe concavo-convex patterns, the concavo-convex patterns are regularlyformed.